This invention relates to vapor recovery systems and, more specifically, to vapor recovery nozzles. The most pertinent prior art known to applicants include U.S. Pat. Nos. 2,908,299; 3,521,679; 3,566,928; 3,581,782; 3,604,478; 3,710,830; 3,710,831; and 3,756,291.
Recent years have seen increasing concern over the presence of hydrocarbons in the air as a source of air pollution. One primary source of such hydrocarbons is the vapor of normally liquid petroleum products such as gasoline or diesel fuel.
Such vapors are typically found in the air space within a vessel over the liquid in the vessel and when the vessel, such as a fuel tank, is partially or wholly filled, such vapors in the air space over the liquid are forced out of the inlet of the vessel into the ambient atmosphere to thereby cause the pollution problem.
Numerous proposals have been made for constructions whereby vessels may be filled and the vapor above such liquid as may be present in the vessel captured as it is driven out of the vessel by the incoming liquid. Typically, such systems include a spout which may be introduced into the inlet of such a vessel and a hood surrounding the spout which embraces the entire periphery of the inlet. The hood is connected to a vapor recovery system so that the vapors received therein are fed through such system and removed without being discharged into the atmosphere. In some cases, the systems rely solely on the displacement of vapor within the vessel by the incoming liquid, while in other systems, a small vacuum is applied in the vapor recovery system to assist in withdrawing the vapor from the vessel.
There have also been a sizable number of proposals for valve-operated nozzles, generally intended for use on petroleum pumps at service stations, for employment in such vapor recovery systems. In general, the various proposals have failed to meet substantial acceptance. Frequently, the same are not adaptable to the wide variety of dimensions of filler tubes for fuel tanks, do not lend themselves to economic manufacture due to bulk or undue complexity, or cannot be suitably used with vapor recovery systems wherein vapor recovery elements may be contaminated by the liquid from which the vapor is formed.